Usage limits are part of the product
A plan may include a message cap, a slower model at peak times or a separate charge for API usage. Check the limit for the work you do.
Seats and sharing
A personal plan is not a team plan. Check whether seats can be added, whether usage is shared and what happens when a seat is removed.
Data and privacy
Check whether your inputs are used for training and what the retention policy is. A cheaper plan may have different data terms.
Annual billing and cancellation
Annual billing can discount the monthly price but commits for a year. Check the refund policy and the notice period.
The alternative cost
Compare the subscription with the price of the same work done manually or with a pay-per-use API. A monthly plan is not automatically cheaper.