a0d929ca_WSRP_v2_0_Specification__Statement_text
[#] CS042 [Section] 5.1.4 [Statement text] 
If the portletState field has a value, the Consumer MUST return this value on subsequent calls using the same portletHandle. Note that such uses can span multiple starting and stopping cycles of the Consumer and therefore this state MUST be persisted by the Consumer until successfully invoking destroyPortlets with the related portletHandle.
WSRP v2.0 Specification
Statement text