No, you will not lose any submission credits that you have left in your account..
If you have any outstanding submission credits they will be added to the new plan that you choose.
For example,
Let's say you have a BASIC Plan and have 5 submission credits remaining.
You decide to upgrade to the PRO Plan.
Three things will happen at the same time.
1. Your BASIC Plan will be cancelled.
2. Your PRO Plan will start (including payment for the PRO Plan).
3. Your PRO Plan submission credits will be added to your account.
You'll end up with 35 submission credits (5 leftover from your BASIC Plan and 30 from your new PRO Plan).
** Based on current plans 08/31/2018
If you have any outstanding submission credits they will be added to the new plan that you choose.
For example,
Let's say you have a BASIC Plan and have 5 submission credits remaining.
You decide to upgrade to the PRO Plan.
Three things will happen at the same time.
1. Your BASIC Plan will be cancelled.
2. Your PRO Plan will start (including payment for the PRO Plan).
3. Your PRO Plan submission credits will be added to your account.
You'll end up with 35 submission credits (5 leftover from your BASIC Plan and 30 from your new PRO Plan).
** Based on current plans 08/31/2018